Outlet boxes for thermal engines are generally installed in the region of the cylinder heads of said engines, or mounted directly thereon, and provide controlled cooling of said cylinder heads, by regulating the flow of cooling liquid in contact therewith.
These thermostats comprise essentially a valve mounted in mobile translation, to block or release an opening in said box, guided over a spindle and subject to the opposed stresses of an elastic means, such as a compression spring, forcing said valve in the closed position and a heat activated means, such as a wax cartridge, forcing said valve in the open position counter to the above-mentioned elastic stress.
Various embodiments of such a water outlet box are already known, but they all have limitations in terms of manufacturing costs and/or complexity of manufacturing and/or installation.
Thus, according to a first known embodiment, the thermostat is enclosed in a metal shell providing the valve seat and an opposed wall portion to absorb stresses, having an external radial edge intended to be squeezed between the two parts constituting said box assembled by screwing, with a peripheral sealing strip placed between them. This results in a complex, costly structure that requires special additional impermeability.
According to a second known embodiment, the box is made of a thermosetting material or of aluminium and comprises an opening forming a valve seat and opposed lips to support the stress-absorbing clamp of the thermostat.
Said box may be made in a single piece being attached directly to the cylinder head or in two parts assembled by mechanical means of connection, with a sealing strip placed between them.
A third existing solution proposes producing the body of the box in a plastics material, which box comprises an opening forming a valve seat and radial tongues to engage the stress-absorbing clamp and temporarily retain the thermostat, between its mounting in the box and fixing said box on the cylinder head. After fixing, the clamp rests directly on said cylinder head, which absorbs all the axial stresses applied in the opposite direction to the valve. Nevertheless, in this last solution, it is also necessary to make a special assembly with a sealing strip interposed.
Consequently, the problem posed consists of overcoming the limitations of the existing solutions set out above and providing a water outlet box incorporating a thermostat in the form of a pre-fabricated module, preferably closed.